DESCRIPTION: The applicant will use molecular genetic, imaging and biophysical techniques to determine how the actin filament network is formed and shaped by actin cross-linking proteins. Mutant cell lines which contain alterations in genes coding for the actin binding proteins ABP-120, ABP-240 and a-actinin as well as myosin II will be studied. Several novel in vitro and in vivo assays will be used to assess the consequences of these alterations in the cytoskeleton.